We started by removing all the grass in the area and leveling the dirt. I decided that the broken mirror looked a little monotonous, so I went down to the dollar store and bought a number of glass pebbles that are supposed to go in the bottom of vases. That brought our total cost for the project up to a whopping five dollars.
Quick-dry concrete sets up very quickly, so you want to do as much planning of your mosaic design as possible before you even mix the concrete. They sell special tacky paper that you can use to lay out large pieces of mosaic. The pieces stick to the paper, and you can flip it all over into the mosaic medium and peel the paper away from the mosaic pieces. I decided to go the do-it-yourself route, so I took six palm-sized pieces of kraft paper and sprayed spray adhesive all over them. Then, placing each piece upside down into the glue, I used round pebbles for flower centers, and oval ones to make petals. At first, it didn't seem like the pebbles were going to stick, but after the adhesive dried, the pebbles stayed on.
Working with concrete is simpler than you think. The key is just to remember to oil your forms. We were working with lengths of 2"x6" boards, and I painted inexpensive vegetable oil on the inside surface of each board. We braced the outside of each board with a couple of bricks to keep it from falling over, then we mixed up the concrete according to the package directions. Working a section at a time, my husband laid the concrete, smoothing the top with a shovel, then I went behind him, embedding the pieces of mirror (which required pulling the wet concrete up over the edges a bit, so that no raw edges would show). I felt like it needed a little more texture, so I added some small round pebbles to form an abstract geometric design alongside the mirror pieces.
When we were working on the front, we measured out the intervals where we would need to place the six mosaic flowers in order for them to wind up even. We then set the pieces (still attached to the kraft paper) behind the forms, so that they could be added at the correct spot. Flipping the paper over, peeling it away and then embedding the pebbles went mostly according to plan, except that two of the papers got wet, which completely negated the spray adhesive.
We wound up with a permanent, attractive border.